1. Field of the Invention
This invention relates to the field of computer processing and, more particularly, to identifying properties of virtual resources to efficiently perform cluster backups and restores of cluster data.
2. Description of the Related Art
In order to protect data, the contents of information servers and end-user systems may be backed up to a data storage subsystem by a backup system configured by an information technology (IT) administrator. In addition to an efficient data backup system, a company may utilize a high availability of services provided by clusters of nodes coupled via a network. With cluster computing, a second node in the cluster provides service when any of at least the following events occur: a first node fails, a first node is chosen to move for load balancing purposes, or a first node is temporarily out of service for upgrades or maintenance service. In addition, migration may occur at a finer granularity level than at a node level, such as at a level of virtual machines (VMs) within the nodes.
A server operating system, for example Windows Server® 2008 R2, may comprise a virtual subsystem that is aware of VMs running locally on a corresponding node, but is unaware of VMs running on other cluster nodes. In addition, the virtual subsystem may not distinguish between highly available (HA) and non-highly available (non-HA) virtual machines (VMs). At least three problems may arise due to these limitations during backup and restore operations on VMs within the cluster. A first problem may occur when a restore operation is performed on a HA VM. Typically, corresponding cluster resources are taken offline prior to restoring the HA VM. The virtual subsystem is unaware whether the corresponding VM is highly available, and therefore, it is unknown whether and which cluster resources are taken offline.
A second problem related to the limitations discussed above is a possibility of backing up the same data multiple times when a cluster shared volume is used in the computing system. The virtual subsystem is unaware of VMs running on other cluster nodes other than the controlling node for the backup operation. The virtual subsystem does not have sufficient information to identify write-protected files within a cluster shared volume. Customers may initially perform a volume-level backup to obtain full volume flat file backups. At a later time, customers may perform an agent-based backup operation of particular data used by a given node. Because a node performing a volume level backup has no knowledge of which portions of a cluster shared volume are used by particular applications on another node, a volume level backup will simply perform a backup of the entire volume. Subsequently, when the agent level backup is performed, the agent level backup will backup data, which was also backed up during the volume level backup.
A third problem related to the limitations discussed above is an IT administrator who is coordinating backup schedules may not have an accurate picture of the cluster over time. The migration and the elevation to high availability of VMs occur over time. Therefore, a daily backup job targeting a given VM may be unable to proceed since the backup job may not know whether the given VM is now highly available and the backup job may not know the current location of the given VM.
In view of the above, methods and mechanisms for identifying properties of virtual resources to efficiently perform cluster backups and restores of cluster data are desired.